Field
The invention generally relates to medical devices and procedures, and more particularly to implantation of a medical device into a body of a patient to ensure the patency of a ureter and minimize patient discomfort.
The invention generally relates to medical devices and procedures, and more particularly to implantation of a medical device into a body of a patient to ensure the patency of a ureter and minimize patient discomfort.
Description of the Related Art
Medical devices such as ureteral stents are used to create a pathway for urinary drainage from a kidney to a urinary bladder of a patient with ureteral obstruction or injury, or to protect the integrity of a ureter in various surgical operations. A number of clinical conditions may produce interruption in urine flow including, for example, intrinsic obstruction of the ureter due to tumor growth, stricture or stones, compression of the ureter due to extrinsic tumor growth, stone fragment impactation in the ureter following Extracorporeal Shock Wave Lithotripsy (ESWL), and ureteral procedures such as ureteroscopy and endopyelotomy. Stents may be used to treat or avoid obstructions of the ureter (such as ureteral stones or ureteral tumors) that disrupt the flow of urine from the kidney to the urinary bladder. Serious obstructions of a urinary tract may cause urine to flow back into the kidney, threatening renal function. The stent may be placed in the ureter to facilitate the flow of urine from the kidney to the urinary bladder and to enable the ureter to heal.
Ureteral stents typically are tubular in shape, terminating in two opposing ends: a kidney distal end and a urinary bladder proximal end. One or both ends of the stent may be coiled in a pigtail spiral or J-shape to prevent the upward and/or downward migration of the stent in a lumen of the ureter due to, for example, the day-to-day physical activity of the patient. The ureteral stent may reside inside the body of the patient for typically three to thirty days, but can be there for as long as one year. A kidney end coil is designed to retain the stent within a kidney or renal pelvis and to prevent the migration of the ureteral stent down the ureter. A urinary bladder end coil is positioned in the urinary bladder and is designed to prevent migration of the ureteral stent upward toward the kidney. The urinary bladder end coil may also be used to aid in retrieval and removal of the ureteral stent.
The use of coils at the kidney distal end and the urinary bladder proximal end in the ureteral stent can result in patient discomfort when the typical indwelling stent comes in contact with these regions of the patient. Typical ureteral stents, particularly the portion positioned in the urinary bladder, may produce adverse effects, including hemorrhage, a continual urge to urinate, and flank pain accompanying reflux of urine back up the ureter due to retrograde pressure when voiding.
Flank pain may be caused from typical ureteral stents during urinary voiding. On the initiation of voiding the urinary bladder, wall muscles contract causing the pressure inside the urinary bladder to rise. Since a typical indwelling ureteral stent holds a ureteral orifice open, this pressure can cause urine to be transmitted to the kidney causing the patient to experience pain. Attempts to mitigate some of these problems associated with ureteral stents include administering systemic pharmaceuticals such as anti-spasmodic drugs that may present additional undesirable side effects. In general, known ureteral stents may cause or contribute to significant patient discomfort and serious medical problems.
Existing solutions to reduce the patient discomfort have focused on reducing the mass in the urinary bladder end coil of the ureteral stent, or using a softer material in place of the coils.
In accordance with the foregoing, there is a need for devices and methods for providing an improved urinary stent that ensures the patency of a ureter of a patient and minimizes patient discomfort in the kidney and bladder areas.